The Negroes in Negroland, the Negroes in America, and Negroes Generally; Also, the Several Races of White Men, Considered as the Involuntary and Predestined Supplanters of the Black Races (New York: G. W. Carleton; London: S. Low, Son, and Co., 1868), by Hinton Rowan Helper

History of the Negro Race in America from 1619 to 1880: Negroes as Slaves, as Soldiers and as Citizens, Together With a Preliminary Consideration of The Unity of The Human Family, an Historical Sketch of Africa, and an Account of The Negro Governments of Sierra Leone and Liberia (2 volumes; New York: G.P. Putnam's Sons, 1883), by George Washington Williams